Atomic force microscopy and atomic force acoustic microscopy characterization of photo-induced changes in some Ge–As–S amorphous films

Amorphous Ge27As13S60, Ge14As27S59 and Ge16As26S58 thin films were prepared by thermal evaporation. Well annealed films were photodarkened by the photons with energy little exceeding the band gap energy. Using Atomic Force Microscopy we observed significant photoexpansion of studied films. Atomic Force Acoustic Microscopy revealed domains like structure of the surface and near surface parts of the samples which one was found to be more disintegrated after illumination.